The APSD measurement of DPIs is typically performed under the same conditions as DDU testing, however a Preseparator is typically interposed between the induction port and stage 0 of cascade impactor to capture the large, non-inhalable carrier particles, to prevent impactor over-loading (when using an NGI or ACI). As for delivered dose testing of DPIs, test flow rate is set on the basis of a 4 kPa pressure drop across the device, to approximate the mean patient inhalation flow rate achieved during clinical use.
Induction Port P1 Measurement Adapter
Used together with the Critical Flow Controller, the Induction Port P1 Measurement Adapter can be placed between the inhaler and the induction port to measure the pressure drop (P1) over the inhaler under test in the absence of a DUSA for DPIs.